<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Title</title>
  <!--
  相对定位：相对于自己原来的位置定位
  -->
  <style>
    div {
      margin: 10px;
      padding: 5px;
      font-size: 14px;
      line-height: 25px;
    }

    .father {
      border: 1px solid #cb0d0d;
    }

    .first {
      border: 1px solid #0093E9;
      background-color: #009399;
      /*相对定位*/
      position: relative;
      top: -20px;
      left: 20px;
    }

    .second {
      border: 1px solid #80D0C7;
      background-color: #80D077;
    }

    .third {
      border: 1px solid #c5c5cb;
      background-color: #c5c5cc;
      position: relative;
      bottom: -20px;
      right: 20px;
    }
  </style>
</head>
<body>
<div class="father">
  <div class="first">第一个盒子</div>
  <div class="second">第二个盒子</div>
  <div class="third">第三个盒子</div>
</div>
</body>
</html>